A method provides a diagnostic on a combined humidity and temperature sensing device including a humidity sensor having a humidity sensing element, a temperature sensor, and a heater. The method comprises obtaining a first temperature and a first relative humidity, heating the humidity sensing element with the heater, obtaining a second temperature and a second relative humidity after heating the humidity sensing element, and determining a difference between the first temperature and the second temperature and a difference between the first relative humidity and the second relative humidity. Diagnostic information representative of a possible malfunction of the humidity sensor is output when the difference between the first temperature and the second temperature is higher than a predetermined temperature difference threshold and the difference between the first relative humidity and the second relative humidity is lower than a predetermined humidity difference threshold.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method for providing a diagnostic on a combined humidity and temperature sensing device, comprising: providing the combined humidity and temperature sensing device including a humidity sensor having a humidity sensing element, a temperature sensor, and a heater; obtaining an external temperature output from an additional temperature sensor different from the temperature sensor, the additional temperature sensor is arranged so as not to be affected by the heater; obtaining a first temperature and a first relative humidity output by the combined humidity and temperature sensing device, the first relative humidity is a function of the first temperature; heating the humidity sensing element with the heater; obtaining a second temperature and a second relative humidity output by the combined humidity and temperature sensing device after heating the humidity sensing element, the second relative humidity is a function of the second temperature; determining a difference between the first temperature and the second temperature and a difference between the first relative humidity and the second relative humidity; outputting diagnostic information representative of a possible malfunction of the humidity sensor when the difference between the first temperature and the second temperature is higher than a predetermined temperature difference threshold and the difference between the first relative humidity and the second relative humidity is lower than a predetermined humidity difference threshold; and outputting a degraded mode information if a possible malfunction of the temperature sensor is determined, the degraded mode information including the external temperature and a relative humidity output by the combined humidity and temperature sensing device as a function of the external temperature.
2. The method of claim 1 , further comprising outputting diagnostic information representative of the possible malfunction of the temperature sensor when the difference between the first temperature and the second temperature is lower than the predetermined temperature difference threshold and the difference between the first relative humidity and the second relative humidity is higher than the predetermined humidity difference threshold.
3. The method of claim 1 , further comprising outputting diagnostic information representative of a possible malfunction of the heater when the difference between the first temperature and the second temperature is lower than the predetermined temperature difference threshold and the difference between the first relative humidity and the second relative humidity is lower than the predetermined humidity difference threshold.
4. The method of claim 3 , further comprising outputting a command for stopping the heater.
5. The method of claim 1 , wherein the external temperature is obtained before heating the humidity sensor and before measuring the first temperature and first relative humidity.
6. The method of claim 5 , further comprising obtaining a local temperature output from the combined humidity and temperature sensing device and, when a difference between the external temperature and the local temperature is above a predetermined temperature difference threshold, outputting diagnostic information representative of a possible malfunction of either the additional temperature sensor or the combined humidity sensing device.
7. The method of claim 1 , further comprising, before heating the humidity sensor, obtaining a first external temperature output from the additional temperature sensor and obtaining a first local temperature and a first relative humidity output from the combined humidity and temperature sensing device.
8. The method of claim 7 , further comprising obtaining a second external temperature output from the additional temperature sensor and a second local temperature and a second relative humidity output from the combined humidity and temperature sensing device when a difference between the first external temperature and the first local temperature is above a first predetermined temperature difference threshold.
9. The method of claim 8 , further comprising, after a predetermined period of time, determining whether a variation between the first external temperature and the second external temperature and a variation between the first local temperature and the second local temperature are both below a second predetermined temperature difference threshold, and determining whether a variation between the first relative humidity and the second relative humidity is below a predetermined humidity difference threshold.
10. The method of claim 9 , wherein the steps of claim 1 are carried out only when the variation between the first external temperature the second external temperature and the variation between the first local temperature and the second local temperature are both determined to be below the second predetermined temperature difference threshold, and the variation between the first relative humidity the and second relative humidity is also determined to be below the predetermined humidity difference threshold.
11. The method of claim 1 , further comprising, as a first step, waiting a predetermined amount of time corresponding to a predefined startup or stabilization time of a system using the combined humidity and temperature sensing device.
12. The method of claim 1 , wherein the steps are only carried out when the first temperature output from the combined humidity and temperature sensing device is within a predetermined temperature validity range and the first relative humidity output from the combined humidity and temperature sensing device is within a predetermined relative humidity validity range.
13. The method of claim 1 , further comprising cycling through the steps a predefined number of times and each cycle is performed a predefined amount of time after a previous cycle.
14. A system, comprising: a combined humidity and temperature sensing device including a temperature sensor, a humidity sensor having a humidity sensing element, and a heater; an additional temperature sensor different from the temperature sensor of the combined humidity and temperature sensing device, the additional temperature sensor is arranged so as not to be affected by the heater; and a processor performing the steps of: obtaining a first temperature and a first relative humidity output by the combined humidity and temperature sensing device, the first relative humidity is a function of the first temperature; heating the humidity sensing element with the heater; obtaining a second temperature and a second relative humidity output by the combined humidity and temperature sensing device after heating the humidity sensing element, the second relative humidity is a function of the second temperature; determining a difference between the first temperature and the second temperature and a difference between the first relative humidity and the second relative humidity; outputting diagnostic information representative of a possible malfunction of the humidity sensor when the difference between the first temperature and the second temperature is higher than a predetermined temperature difference threshold and the difference between the first relative humidity and the second relative humidity is lower than a predetermined humidity difference threshold; and outputting a degraded mode information if a possible malfunction of the temperature sensor is determined, the degraded mode information including an external temperature output from the additional temperature sensor and a relative humidity output by the combined humidity and temperature sensing device as a function of the external temperature.
15. The system of claim 14 , wherein the additional temperature sensor is external to the combined humidity and temperature sensing device.
16. The system of claim 14 , wherein the additional temperature sensor is internal to the combined humidity and temperature sensing device.
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March 20, 2018
March 16, 2021
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